Compiler/MSP430G2553: PROGRAMME for reciever UART

Hi Anthonis,

The reason it keeps sending 'b' or 'c' is that you have the "UCA0TXBUF = UCA0RXBUF" in the while(1) loop.

I suggest you to use the code example for the G2553 UART communication. You can find it in the MSPWare at: http://www.ti.com/tool/MSPWARE. There it uses the interrupt to handle the uart operation thus the received character only sent out once.

Also attached the code example here for quick reference.

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//******************************************************************************
//   MSP430G2xx3 Demo - USCI_A0, 9600 UART Echo ISR, DCO SMCLK
//
//   Description: Echo a received character, RX ISR used. Normal mode is LPM0.
//   USCI_A0 RX interrupt triggers TX Echo.
//   Baud rate divider with 1MHz = 1MHz/9600 = ~104.2
//   ACLK = n/a, MCLK = SMCLK = CALxxx_1MHZ = 1MHz
//
//                MSP430G2xx3
//             -----------------
//         /|\|              XIN|-
//          | |                 |
//          --|RST          XOUT|-
//            |                 |
//            |     P1.2/UCA0TXD|------------>
//            |                 | 9600 - 8N1
//            |     P1.1/UCA0RXD|<------------
//
//   D. Dang
//   Texas Instruments Inc.
//   February 2011
//   Built with CCS Version 4.2.0 and IAR Embedded Workbench Version: 5.10
//******************************************************************************
#include <msp430.h>

int main(void)
{
  WDTCTL = WDTPW + WDTHOLD;                 // Stop WDT
  if (CALBC1_1MHZ==0xFF)					// If calibration constant erased
  {											
    while(1);                               // do not load, trap CPU!!	
  }
  DCOCTL = 0;                               // Select lowest DCOx and MODx settings
  BCSCTL1 = CALBC1_1MHZ;                    // Set DCO
  DCOCTL = CALDCO_1MHZ;
  P1SEL = BIT1 + BIT2 ;                     // P1.1 = RXD, P1.2=TXD
  P1SEL2 = BIT1 + BIT2 ;                    // P1.1 = RXD, P1.2=TXD
  UCA0CTL1 |= UCSSEL_2;                     // SMCLK
  UCA0BR0 = 104;                            // 1MHz 9600
  UCA0BR1 = 0;                              // 1MHz 9600
  UCA0MCTL = UCBRS0;                        // Modulation UCBRSx = 1
  UCA0CTL1 &= ~UCSWRST;                     // **Initialize USCI state machine**
  IE2 |= UCA0RXIE;                          // Enable USCI_A0 RX interrupt

  __bis_SR_register(LPM0_bits + GIE);       // Enter LPM0, interrupts enabled
}

//  Echo back RXed character, confirm TX buffer is ready first
#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector=USCIAB0RX_VECTOR
__interrupt void USCI0RX_ISR(void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(USCIAB0RX_VECTOR))) USCI0RX_ISR (void)
#else
#error Compiler not supported!
#endif
{
  while (!(IFG2&UCA0TXIFG));                // USCI_A0 TX buffer ready?
  UCA0TXBUF = UCA0RXBUF;                    // TX -> RXed character
}